1 Reply Rule. In an online argument, if a conclusion hasn't been reached within one reply to each other then a conclusion won't be reached. This is because the most compelling arguments are often given first, and if they don't bite then no arguments will. And even if you do convince the opponent they still won't admit to being wrong on the internet.

Either used alone or at the end of a post, meaning the poster disagrees but acknowledges that starting a long argument will just be a waste of time.